1. Field of the Invention
The present invention relates generally to all optical networks, and more particularly to an all optical network that uses broadcast and select ring architecture with various configurations to protect ring fibers, WDM equipment and client equipment.
2. Description of the Related Art
Broadcast-and-select technique has been used in linear, star, and ring optical networks. In a broadcast-and-select optical network, multiple wavelengths in a fiber are simultaneously broadcast to multiple destinations via one or more optical couplers. At each destination, there is either a tunable filter or a fixed filter/demultiplexer to perform the “select” function.
However, optical ring networks usually require protection on one or all of the following facilities: (i) optical fibers on the ring; (ii) WDM equipment; and (iii) client equipment, including but not limited to SONET/SDH, Gigabit Ethernet, Fiber Channel and the like. There is no method to achieve any of these protections in a broadcast and select optical network.
There is a need for a fully-protected broadcast and select architecture in an all optical fiber ring network. There is a further need for a passive fiber ring network that does not have active elements. When there are in-line optical amplifiers on a ring network, there is a further need for an all optical fiber ring network that has minimal fiber ring lasing or coherent cross-talk on the ring. There is still a further need for an all optical fiber ring network that eliminates in-line amplifier gain saturation on the ring by equalizing all wavelength powers at the input of each in-line amplifier.